Arc-lamp.



C. E. HARTHAN.

ARC LAMP.

APPLICATION FILED AUG-12.1915.

1,229,950. Patented June 12, 1917.

lm/encor 1 Charles ELHar'C han,

HIS Attorney.

UNITED STATES PATENT oEEIoE.

CHARLES E. HARTHAN, OIF'LYNIN', MASSACHUSETTS, ASSIGNOR To GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ARC-LAMP.

Specification of Letters Patent. 'Patented June 12, 1917.

Application filedAugust 12, 1915. Serial No. 45,144.

To all whom it may concern:

Be it known that 1, CHARLES E. HARTHAN, a citizen of the United States, residing at Lynn, county of Essex, State of Massachusetts, have invented'certain new and useful Improvements in Arc-Lamps, of which the following is a specification.

My invention has reference to an improvement in an arc lamp, and more particularly to a direct current series arc lamp of the differential type, and is especially applicable to are lamps of the flame type, although it is in no way limited in its application to lamps of this character.

With direct current series are lamps of the differential type, that is lamps in which the feeding of the electrodes is 'caused by the combined action of a series and a shunt magnet, difiiculty has hitherto been experienced because of the sluggish regulation thereof. In a differential series lamp the current in the series magnet is, of course, constant, and after the arc is once established-the feeding of the electrodes is brought about by variations in the current in the shunt magnet as a result of-variations in the voltage of the are which accompany changes in the arc length.

When, during any phase of operation of lamps of this type, the feeding mechanism and parts connected thereto, including the electrodes, are in a state of rest, the friction and the inertia of the parts, make the lamp insensitive to slight variations of the current from the normal in the shunt magnet, such as result when the arc unduly lengthens, or when the lamp has over-fed, and the proper regulation is thereby impeded. In alternating current are lamps no such difficulty is ordinarily experienced, becau'se the feeding mechanism is always in a state of vibration, and any change of current, however slight, in the shunt magnet will produce the desired movement of the feeding mechanism and will bring about a feeding operation. V I

My invention overcomes the difiiculties referred to by the provision of means responsive to slight variations in the current of the shunt magnet and which preferably comprise a lost motion connection between the armature of the shunt magnet and the feeding mechanism for mechanically provoking a feeding operation.

For a fuller understanding of my invention, reference may be had to the accompanying drawing, which is a diagrammatic view of an arc lamp embodying my invention.

. Referring, now, to the drawing, 1 and 2 are the electrodes, which are caused to move in step by flexible connections 3 and 4, the ends ofwhich are secured to the upper and lower electrodes, respectively, and the other ends of which pass over the sheaves of a pulley 5, the connection 4: being guided by a pulley 6. The feeding mechanism of the lam comprises an arm 7, whichis. pivoted to the shaft of the pulley 5, to which arm is pivoted a cam 8 which engages a rim on the pulley 5. The construction and operation of this clutch is fully disclosed in an application of Reginald G. Standerwick, No. 727,359, which was filed in the U. S. Patent Office October 23, 1912, to which reference may be had for more complete details of construction. The outer end of the arm 7 is connected, by means of a link 9, to an actuating member or lever 10, pivoted at 11 to a stationary part of the lamp. The lever 10 is actuated by the armatures of the series magnet 12 and the shunt magnet 13, respectively. One terminal of the series magnet 12 is connected to one of the supply conductors 14, while the other terminal thereof is connected by a conductor 15 to the lower electrode holder 16. The shunt magnet 13' is connected at one terminal to the other supply conductor 17, while the other terminal thereof is connected to the lower electrode holder 16. The armature 18 of the series magnet is directly connected to one end of the arm 10, being pivoted thereto at 19. The armature 20 of the shunt magnet is connected to the otherend of the arm 10 through a lost motion connection comprising a bracket 21, in the form of a strap, in which is received a pin 22 secured to a bar 23 pivoted to the arm 10 at 24. The upper end of the bar 23 is received in an opening 25 in the central portion 26 of the armature of the shunt magnet. The series magnet 12 is preferably provided with a second winding 27 of a material having a zero or nearly zero temperature coefficient, and differentially wound with respect to the main series coil in order to compensate for variations in voltage across the arc, which result from variations of resistance of the shunt magnet, due to changes in resistance. thereof which accompany the thermal variations. The lever 10 controls a cut-out of the usual type comprising a bridging contact 28 which engages the stationary contacts 29, to which are connectedconductor's 30 and 31 leading to the supply conductors-14 and 17 respectively the conductor 30 includes a resistance 30'.

The operation of the lamp illustrated in the drawing and embodying my invention is as follows: When the lamp is without current the electrodes are in engagement. WVhen current is turned on the lamp,-the series magnet is energized, and lifts its end of the lever 10, thereby lifting the link 9 and the outer end of the arm 7 and causing a rotation of thepulley 5, thereby separating the electrodes to establish the arc. Now, when the arc is of normal length, and the current in the shunt magnet 18 of normal value, the armature 20 of the shunt magnet floats in the magnetic field thereof, and the pin 22 is free within the bracket 21. But in case of a variation of voltage across the arc, such as would result from over-feeding of the lamp, or when a feeding operation is reuired, there is a corresponding variation in t e voltage across the shunt magnet and in the current thereof. The movement of the arm will then cause the pin 22 to engage the bracket 21, or the armature itself, and this mechanical action of the armature will cause a movement of the lever 10, to provoke a feeding o eration.

In accor ance with. the provisions of the patent statutes, I have described the principle of operation of myinvention, together the shunt magnet and the actuating mem ber for moving said member in either-direc tion'.

2. In an arc lamp, a feeding mechanism comprising an actuating member and series and shunt magnets, and a lost motion connection between the armature of the shunt magnet andsaid actuating member for moving said member in either direction, the connection between the armature and said member being normally inoperative and the armature normally floating in the field of the magnet.

3. In an arc lamp, a feeding mechanism for the lamp comprising an actuating member and series and shunt magnets, and a lost motion connection between the armature of said shunt magnet and said member comprising a pin carried by the one and a strap carried-by the other and inclosing the pin whereby the actuating member is moved in CHARLES E. HARTHAN. 

